The vote was triggered when 48 Tory MPs wrote a letter demanding the vote. May will be forced to step down if 158 of the Conservative Party’s 315 MPs support it. If she wins the vote, which is set to take place at 1 p.m. EST, she cannot be challenged for another year.

According to the BBC, May is confident she has the backing of enough MPs to survive the vote. However, the ballot is secret, so it’s possible Tory MPs will say they support May in public but do the opposite when it comes time to cast their votes.

"I will contest that vote with everything I've got" – UK Prime Minister Theresa May says she will "stand ready to finish the job" as no-confidence vote is triggered

Multiple unconfirmedreports also indicated May would step down before the next election. A Downing Street spokesperson addressed those rumors Wednesday, saying May “doesn’t believe the vote today is about who leads the party in the next election.”

“It’s about whether it’s sensible to change leader at this point in the [Brexit] negotiations,” they said.

Any leadership challenge would be seen as an impatient power grab — as well as strategically useless, since the new leader would have to deal with the remaining Brexit talks. If, however, May loses the vote, it could fundamentally alter the nature of those negotiations.

The EU has already said it won’t renegotiate the deal, so if a Brexit hardliner like Boris Johnson replaced May, it would likely lead to a situation in which no deal is negotiated before the March 29 deadline. In this worse-case scenario, both British trade to the EU and supply chains of perishable items to the U.K. Regulations would disappear overnight meaning, among other things, that aircraft in the U.K. could not fly through the EU, and that materials needed for cancer treatments could not be imported into the U.K.

As the Guardian’s Jonathan Freedland noted Wednesday, even if a hardliner does succeed May, they still have to pass a deeply unpopular Brexit bill through a Parliament where the Conservative party does not have an outright majority.

“…Every second of [the next] 14 weeks should be spent striving to come up with a plan of action that MPs could agree on,” he wrote. “…But instead of working day and night to avert that disaster, the Conservative party has decided to squander precious time with what several loyalist ministers are calling an act of self-indulgence.”